The present disclosure relates to an actuating member for causing an elongated member for medical use to perform a predetermined curving motion, and a medical instrument including the actuating member.
In the medical field, flexible elongated members are generally used for administration of a drug into a living body, suction or injection of various fluids, introduction of a medical instrument into a living body, or other similar purposes. Such an elongated member is inserted into a lumen (e.g., a blood vessel or a body cavity) in a living body and is guided along a curved path, such as the lumen, to a target site such as a treatment site, or the vicinity thereof, in the living body. Therefore, the elongated member may be used in the state of having incorporated therein an actuating member for a curving operation that can be put into an arbitrary curving operation through an operator's hand operation (see, for example, Japanese Patent Laid-Open No. 2008-142199).
In Japanese Patent Laid-Open No. 2008-142199, an actuating member which includes an operation wire connected to an insertion part (elongated member) to be inserted into a living body, a pulley having the operation wire wound thereon, and a curving operation knob (operation member) for putting the pulley into rotation, and an endoscope in which the actuating member is incorporated are described. The actuating member curves the elongated member by pushing/pulling the operation wire through rotating the curving operation knob, which is disposed at a proximal side of the endoscope, about an axis orthogonal to an axial direction of the elongated member.
In the actuating member according to the related art such as the one described in Japanese Patent Laid-Open No. 2008-142199, however, the elongated member is curved with a radius of curvature being gradually decreased as the operation amount of the operation member increases. Therefore, it is impossible to curve the elongated member with a small radius of curvature at a stage where the operation amount is still small, or to curve the elongated member with a large radius of curvature at a stage where the operation amount has become large. Accordingly, the elongated member cannot be appropriately curved in conformity with a target site in a living body.